Revision a98fdcef941e107eeabae622d85a1f476f25a160 authored by Oleg Nesterov on 14 January 2008, 21:02:37 UTC, committed by Linus Torvalds on 14 January 2008, 21:23:00 UTC
Commit 84427eaef1fb91704c7112bdb598c810003b99f3 (remove task_ppid_nr_ns) moved the task_tgid_nr_ns(task->real_parent) outside of lock_task_sighand(). This is wrong, ->real_parent could be freed/reused. Both ->parent/real_parent point to nothing after __exit_signal() because we remove the child from ->children list, and thus the child can't be reparented when its parent exits. rcu_read_lock() protects ->parent/real_parent, but _only_ if we know it was valid before we take rcu lock. Revert this part of the patch. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 4fd3670
msync.c
/*
* linux/mm/msync.c
*
* Copyright (C) 1994-1999 Linus Torvalds
*/
/*
* The msync() system call.
*/
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/file.h>
#include <linux/syscalls.h>
#include <linux/sched.h>
/*
* MS_SYNC syncs the entire file - including mappings.
*
* MS_ASYNC does not start I/O (it used to, up to 2.5.67).
* Nor does it marks the relevant pages dirty (it used to up to 2.6.17).
* Now it doesn't do anything, since dirty pages are properly tracked.
*
* The application may now run fsync() to
* write out the dirty pages and wait on the writeout and check the result.
* Or the application may run fadvise(FADV_DONTNEED) against the fd to start
* async writeout immediately.
* So by _not_ starting I/O in MS_ASYNC we provide complete flexibility to
* applications.
*/
asmlinkage long sys_msync(unsigned long start, size_t len, int flags)
{
unsigned long end;
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
int unmapped_error = 0;
int error = -EINVAL;
if (flags & ~(MS_ASYNC | MS_INVALIDATE | MS_SYNC))
goto out;
if (start & ~PAGE_MASK)
goto out;
if ((flags & MS_ASYNC) && (flags & MS_SYNC))
goto out;
error = -ENOMEM;
len = (len + ~PAGE_MASK) & PAGE_MASK;
end = start + len;
if (end < start)
goto out;
error = 0;
if (end == start)
goto out;
/*
* If the interval [start,end) covers some unmapped address ranges,
* just ignore them, but return -ENOMEM at the end.
*/
down_read(&mm->mmap_sem);
vma = find_vma(mm, start);
for (;;) {
struct file *file;
/* Still start < end. */
error = -ENOMEM;
if (!vma)
goto out_unlock;
/* Here start < vma->vm_end. */
if (start < vma->vm_start) {
start = vma->vm_start;
if (start >= end)
goto out_unlock;
unmapped_error = -ENOMEM;
}
/* Here vma->vm_start <= start < vma->vm_end. */
if ((flags & MS_INVALIDATE) &&
(vma->vm_flags & VM_LOCKED)) {
error = -EBUSY;
goto out_unlock;
}
file = vma->vm_file;
start = vma->vm_end;
if ((flags & MS_SYNC) && file &&
(vma->vm_flags & VM_SHARED)) {
get_file(file);
up_read(&mm->mmap_sem);
error = do_fsync(file, 0);
fput(file);
if (error || start >= end)
goto out;
down_read(&mm->mmap_sem);
vma = find_vma(mm, start);
} else {
if (start >= end) {
error = 0;
goto out_unlock;
}
vma = vma->vm_next;
}
}
out_unlock:
up_read(&mm->mmap_sem);
out:
return error ? : unmapped_error;
}
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